Computed tomography scan (also called a CT or CAT scan)--A diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays. A CT scan provides information about bone, muscle, and fat. It is also used to assist the physician in locating the exact area for a biopsy.

Magnetic resonance imaging (MRI)--A diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body. MRI scans provide detailed information about soft tissue, the bone marrow cavity, and bone tumors.

Bone densitometry--A noninvasive, evaluation procedure that uses x-rays to measure bone mass, or the weight of the skeleton. The amount of bone in the skeleton determines how strong it is. Bone densitometry is often used to measure bone mass in the spine, hips, and arms, as these are the areas most likely to fracture when bone mass is low. Bone densitometry is not used to provide a diagnosis, but is used in combination with other procedures, along with personal and family medical history, to provide information toward or to support a diagnosis.

Radionuclide bone scan--Technetium-99, a radioactive material, is used in a radionuclide bone scan. Bone tumors and some other abnormalities absorb the material and a special camera is used to produce an image using a computer. The bone scan is used to pinpoint the location of bone tumors, as well as to detect spread to other bones.

Biopsy--A procedure in which tissue samples are removed (with a needle or during surgery) from the body for examination under a microscope; to determine if cancer or other abnormal cells are present. There are two types of biopsy, including the following:

Needle biopsy--A small needle is inserted into the abnormal area in almost any part of the body, guided by imaging techniques, to obtain a tissue biopsy. This type of biopsy can provide a diagnosis without surgical intervention.

Open biopsy--A surgical procedure in which an incision is made through the skin to expose the tumor and allow a sample of tissue to be cut or scraped away.